Yamaha TRX850 Enthusiasts Forum

Morning Chaps, i the project bike is up and running but i wanna adjust the valves, i think they need adjusting. Do i really need to take the cam shafts off to do this ? Do you guys know any easy way ... how do you guys do it.

Cheers

Yes you really do need to take the cams out to do this.

You measure the clearances with the cams in. If any clearances are out of spec you then have to remove the cams to check what size shims are fitted.

There is no way of doing this without removing the cams. You will see why when you try.

Or you could read the manual. Drawing at the bottom of page 3-7.

PLEASE write down what each one needs BEFORE you remove a cam. Label them nice and clearly.

Get a feeler gauge between the cam lobe and the "bucket" and measure the clearance, make sure its in spec. If its too much, ie: you can put a thick gauge in, write down by how much, so you know how much to mod your shim.

When you take the bucket off, there will be a small disk. That is your shim. It will have a faint number on it. Add the 2 numbers together to get your new shim thickness, go buy new ones.

Re tension cam and make SURE you put it on correctly, mark the chain / gears with a marker ("texta" if your aussie) so you dont screw up.

Should be an afternoon of work with some beers.

Take pics and do a guide here if you want, tell us of your endevours !

theres 2 ways to do it. the easy way is also quite expensive, take it to a mechanic

the other way is as described above. its not hard to do. just gotta know what to do first. get a nice a4 piece of paper and draw circles for each vlave in the layout of the engine and write the size of the feeler guage that went in, that way you can work out what sizes you need.

Aaa, thanks guys, i thought i had to take off the cam shafts (said so in the book) i was hoping there was a an easy way. No matter, sounds like fun. I might do what quan-Time suggested and that is do a how to.

Just one question, where would i buy these shims ?

any yamaha dealers can get them for you. of you let me know the size you need i'll pm you the yamaha part numbers.

Most motorcycle dealers will have them - they are 9.48mm dia shims (not 7.48!!!!!!!). They're used on many bikes.

There's an American bunch called Hotcams inc that sell kits - you may find a dealer near you - let google be your friend!

Hotcams offer a wider range of sizes than Yamaha, who only go up to 240.

I really should have done all this when the engine was out, now its such a pain.

Agreed - it's easy with the motor out. It may help to remove the carbs and airbox but then it may just be so much easier to drop the motor in the long run.

Thats right, it only takes about an hour to drop it, two to put it back in.